Method and apparatus for managing group communications

ABSTRACT

A method and apparatus for managing group communications are disclosed. A wireless transmit/receive unit (WTRU) may receive the same data using multiple-input multiple output (MIMO) transmission from each of a plurality of synchronized network nodes. The synchronized network nodes may transmit the same data in a synchronized manner. The WTRU may transmit feedback information, including negative acknowledgements (NACKs) and channel quality indicators, to a single one of the plurality of synchronized network nodes. In addition, the feedback information may not be transmitted to the other synchronized network nodes. In response to the transmitted channel quality indicators, the WTRU may receive the same data again from the synchronized network nodes. The synchronized network nodes may transmit the same data again in a synchronized manner. Further, the same data may be received by a plurality of WTRUs. Also, the WTRU may be in a group of a plurality of groups of WTRUs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/392,052 filed Jun. 12, 2012, which is the U.S. National Stage ofInternational Application No. PCT/US2010/046648 filed Aug. 25, 2010,which claims the benefit of U.S. Provisional Application Ser. No.61/236,645 filed Aug. 25, 2009, the contents of which are herebyincorporated by reference herein.

FIELD OF INVENTION

The present invention is related to wireless communications.

BACKGROUND

Dedicated feedback channels have been introduced to improve performancefor multicast services and broadcast services, such as EnhancedMulticast and Broadcast Services (E-MBS) for 802.16m and evolvedMulticast Broadcast Multimedia Systems (eMBMS) for 3rd GenerationPartnership Project (3GPP) High Speed Packet Access (HSPA) and Long TermEvolution (LTE) and to allow the service provider to determine, forexample, transmission parameters for various services, including forexample, broadcast services.

For dedicated feedback channels, each WTRU may be assigned its ownresources for feedback. While it may be possible to reduce WTRU batteryconsumption by, for example, only transmitting negativeacknowledgements, the resources cannot be used for other WTRUs.Moreover, while this method allows the base station to know the exactidentity of the WTRU, providing feedback for a large number of WTRUsrequires a prohibitive amount of uplink resources.

SUMMARY

A method and an apparatus for managing group communications aredisclosed. The example methods disclose forming subscriber groups,signaling of group assignments, grouping physical channels, assigninglogical or physical channels to subscriber groups, and defining triggersfor activating channels.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description, given by way of example and to be understood inconjunction with the accompanying drawings wherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 2A is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2B is another system diagram of an example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 1A;

FIG. 2C is yet another system diagram of an example radio access networkand an example core network that may be used within the communicationssystem illustrated in FIG. 1A;

FIG. 3 is a flow diagram of a process for providing feedback for adownlink shared service via a downlink shared channel in accordance withone embodiment;

FIG. 4 shows one possible power variation scheme of an HS-PDSCH;

FIG. 5 shows an example flow diagram of a process for providing feedbackfor a downlink shared service transmitted to a plurality of WTRUs viaHSDPA in accordance with another embodiment;

FIG. 6 shows an example flow diagram of an example process of evaluatinga transmission criterion for transmitting a P-RAFCH; and

FIG. 7 shows an example mapping between subscribers and physicalchannels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 2A is a system diagram of a RAN 204 and a core network 206according to an embodiment. A RAN 204 may employ a UTRA radio technologyto communicate with WTRUs 202 a, 202 b, 202 c over an air interface 216.The RAN 204 may also be in communication with the core network 206. Asshown in FIG. 2A, the RAN 204 may include Node-Bs 240 a, 240 b, 240 c,which may each include one or more transceivers for communicating withthe WTRUs 202 a, 202 b, 202 c over the air interface 216. The Node-Bs240 a, 240 b, 240 c may each be associated with a particular cell (notshown) within the RAN 204. The RAN 204 may also include RNCs 242 a, 242b. It will be appreciated that the RAN 204 may include any number ofNode-Bs and RNCs while remaining consistent with an embodiment.

As shown in FIG. 2A, the Node-Bs 240 a, 240 b may be in communicationwith the RNC 242 a. Additionally, the Node-B 240 c may be incommunication with the RNC 242 b. The Node-Bs 240 a, 240 b, 240 c maycommunicate with the respective RNCs 242 a, 242 b via an Iub interface.The RNCs 242 a, 242 b may be in communication with one another via anIur interface. Each of the RNCs 242 a, 242 b may be configured tocontrol the respective Node-Bs 240 a, 240 b, 240 c to which it isconnected. In addition, each of the RNCs 242 a, 242 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 206 shown in FIG. 2A may include a media gateway (MGW)244, a mobile switching center (MSC) 246, a serving GPRS support node(SGSN) 248, and/or a gateway GPRS support node (GGSN) 250. While each ofthe foregoing elements are depicted as part of a core network 206, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 242 a in the RAN 204 may be connected to the MSC 246 in the corenetwork 206 via an IuCS interface. The MSC 246 may be connected to theMGW 244. The MSC 246 and the MGW 244 may provide the WTRUs 202 a, 202 b,202 c with access to circuit-switched networks, such as the PSTN 208, tofacilitate communications between the WTRUs 202 a, 202 b, 202 c andtraditional land-line communications devices.

The RNC 242 a in the RAN 204 may also be connected to the SGSN 248 inthe core network 206 via an IuPS interface. The SGSN 248 may beconnected to the GGSN 250. The SGSN 248 and the GGSN 250 may provide theWTRUs 202 a, 202 b, 202 c with access to packet-switched networks, suchas the Internet 210, to facilitate communications between and the WTRUs202 a, 202 b, 202 c and IP-enabled devices.

As noted above, the core network 206 may also be connected to thenetworks 212, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 2B is a system diagram of a RAN 254 and a core network 256according to another embodiment. The RAN 254 may employ an E-UTRA radiotechnology to communicate with the WTRUs 252 a, 252 b, 252 c over theair interface 266. The RAN 254 may also be in communication with thecore network 256.

The RAN 254 may include eNode-Bs 270 a, 270 b, 270 c, though it will beappreciated that the RAN 254 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 270 a, 270 b, 270c may each include one or more transceivers for communicating with theWTRUs 252 a, 252 b, 252 c over the air interface 266. In one embodiment,the eNode-Bs 270 a, 270 b, 270 c may implement MIMO technology. Thus,the eNode-B 270 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 252 a.

Each of the eNode-Bs 270 a, 270 b, 270 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 2B, theeNode-Bs 270 a, 270 b, 270 c may communicate with one another over an X2interface.

The core network 256 shown in FIG. 2B may include a mobility managementgateway (MME) 272, a serving gateway 274, and a packet data network(PDN) gateway 276. While each of the foregoing elements are depicted aspart of the core network 256, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 272 may be connected to each of the eNode-Bs 270 a, 270 b, 270 cin the RAN 254 via an S1 interface and may serve as a control node. Forexample, the MME 272 may be responsible for authenticating users of theWTRUs 252 a, 252 b, 252 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 252 a,252 b, 252 c, and the like. The MME 272 may also provide a control planefunction for switching between the RAN 254 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 274 may be connected to each of the eNode Bs 270 a,270 b, 270 c in the RAN 254 via the S1 interface. The serving gateway274 may generally route and forward user data packets to/from the WTRUs252 a, 252 b, 252 c. The serving gateway 274 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 252 a,252 b, 252 c, managing and storing contexts of the WTRUs 252 a, 252 b,252 c, and the like.

The serving gateway 274 may also be connected to the PDN gateway 146,which may provide the WTRUs 252 a, 252 b, 252 c with access topacket-switched networks, such as Internet 260, to facilitatecommunications between the WTRUs 252 a, 252 b, 252 c and IP-enableddevices.

The core network 256 may facilitate communications with other networks.For example, the core network 256 may provide the WTRUs 252 a, 252 b,252 c with access to circuit-switched networks, such as the PSTN 258, tofacilitate communications between the WTRUs 252 a, 252 b, 252 c andtraditional land-line communications devices. For example, the corenetwork 256 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 258. In addition, the corenetwork 256 may provide the WTRUs 252 a, 252 b, 252 c with access to thenetworks 262, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 2C is a system diagram of the RAN 284 and a core network 286according to another embodiment. The RAN 284 may be an access servicenetwork (ASN) that employs IEEE 802.16 radio technology to communicatewith the WTRUs 282 a, 282 b, 282 c over an air interface 294. As will befurther discussed below, the communication links between the differentfunctional entities of the WTRUs 282 a, 282 b, 282 c, the RAN 284, andthe core network 286 may be defined as reference points.

As shown in FIG. 2C, the RAN 284 may include base stations 280 a, 280 b,280 c, and an ASN gateway 296, though it will be appreciated that theRAN 284 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 280 a, 280 b,280 c may each be associated with a particular cell (not shown) in theRAN 284 and may each include one or more transceivers for communicatingwith the WTRUs 282 a, 282 b, 282 c over the air interface 294. In oneembodiment, the base stations 280 a, 280 b, 280 c may implement MIMOtechnology. Thus, the base station 280 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 282 a. The base stations 280 a, 280 b, 280 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 296 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 286, and the like.

The air interface 294 between the WTRUs 282 a, 282 b, 282 c and the RAN284 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 282 a, 282 b, 282 cmay establish a logical interface (not shown) with the core network 286.The logical interface between the WTRUs 282 a, 282 b, 282 c and the corenetwork 286 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 280 a, 280 b,280 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 280 a, 280 b,280 c and the ASN gateway 296 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs282 a, 282 b, 282 c.

As shown in FIG. 2C, the RAN 284 may be connected to the core network286. The communication link between the RAN 284 and the core network 286may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 286 may include a mobile IP home agent(MIP-HA) 298, an authentication, authorization, accounting (AAA) server297, and a gateway 299. While each of the foregoing elements aredepicted as part of the core network 286, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA 298 may be responsible for IP address management, and mayenable the WTRUs 282 a, 282 b, 282 c to roam between different ASNsand/or different core networks. The MIP-HA 298 may provide the WTRUs 282a, 282 b, 282 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 282 a, 282b, 282 c and IP-enabled devices. The AAA server 297 may be responsiblefor user authentication and for supporting user services. The gateway299 may facilitate interworking with other networks. For example, thegateway 299 may provide the WTRUs 282 a, 282 b, 282 c with access tocircuit-switched networks, such as the PSTN 288, to facilitatecommunications between the WTRUs 282 a, 282 b, 282 c and traditionalland-line communications devices. In addition, the gateway 299 mayprovide the WTRUs 282 a, 282 b, 282 c with access to the networks 292,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 2C, it will be appreciated that the RAN 284may be connected to other ASNs and the core network 286 may be connectedto other core networks. The communication link between the RAN 284 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 282 a, 282 b, 282 cbetween the RAN 284 and the other ASNs. The communication link betweenthe core network 106 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

In general, a WTRU may include a transmitter, a receiver, a decoder, aCQI measurement unit, a memory, a controller, and an antenna. The memoryis provided to store software including operating system, application,etc. The controller is configured to perform a method of sendingfeedback for a downlink shared service. The receiver and the transmitterare in communication with the controller. The antenna is incommunication with both the transmitter and the receiver to facilitatethe transmission and reception of wireless data.

The receiver receives signals from a Node-B. The decoder decodes thereceived signal from the Node-B. The decoder may decode a high speedshared control channel (HS-SCCH) signal while the WTRU is in a Cell_FACHstate. The decoder may decode a downlink transmission on a high speedphysical downlink shared channel (HS-PDSCH) if the WTRU 100 successfullydecodes an identity (ID) of the WTRU on the signal on the HS-SCCH. Thetransmitter sends feedback, (i.e., a CQI or an acknowledgement based onthe decoding of the downlink transmission), to a Node-B via acontention-based shared feedback channel, which will be explained indetail below. The CQI measurement unit outputs a CQI, which will beexplained in detail below.

In general, a Node-B includes a encoder, a transmitter, a receiver, acontroller, and an antenna. The controller is configured to perform amethod of estimating a number of WTRUs in a cell. The transmitter andthe receiver are in communication with the controller. The antenna is incommunication with both the transmitter and the receiver to facilitatethe transmission and reception of wireless data.

The encoder encodes data stream(s) for transmission. The transmittersends a downlink transmission including the encoded data stream(s) for adownlink shared service to a plurality of WTRUs via a downlink sharedchannel. The controller controls a downlink transmit power and/or an MCSon the downlink shared channel so that the downlink transmissions aretransmitted to the WTRUs with a high likelihood of success of beingreceived. The receiver receives feedback from the WTRUs via acontention-based shared feedback channel.

In general, subscribers to a certain service may use a common feedbackchannel to send a pre-defined signal upon meeting certain conditionsthat may include errors, signal levels, or a response to polling (forcounting purposes). This may be further conditioned on the success of anexperiment with a prescribed probability. In all of these cases it isassumed that it isn't essential that the base station knows the identityor the exact number of wireless transmit/receive units (WTRUs) that havesignaled on the common channel, rather a rough estimate of the number ofWTRUs or even the mere fact that one or more WTRUs have done so maysuffice.

The common feedback channel may be a physical channel that carries onebit, where the logical meaning of the bit may be defined by the basestation. It may be constructed such that an event of 2 or more WTRUssignaling the same channel at the same time may be interpreted by thebase station as “one or more”. One or more physical channels may begrouped into a logical channel.

FIG. 3 is a flow diagram of a process 300 for providing feedback for adownlink shared service via a downlink shared channel in accordance withone embodiment. A WTRU is scheduled to receive a downlink transmissionvia a downlink shared channel for a downlink shared service that isprovided to a plurality of WTRUs from a Node-B (302). The WTRU decodesthe downlink transmission (304). If the decoding is not successful, theWTRU sends a pre-defined burst signifying a negative acknowledgement(NACK) to the Node-B via a contention-based shared feedback channel(306). The pre-defined burst may be sent only once without requiring anacknowledgement from the Node-B. If the decoding is successful, the WTRUdoes not send feedback, (i.e., an ACK is implicit).

An uplink shared feedback channel, a physical random access feedbackchannel (P-RAFCH), is introduced for sending the feedback from the WTRUto the Node-B. The P-RAFCH is a contention-based random access channel.For example, at least one P-RAFCH may be associated with each HS-SCCH inthe downlink. If several downlink shared services are supported over theHS-PDSCH(s), a set of P-RAFCHs are provided for the downlink sharedservices and each P-RAFCH may be dedicated to a particular downlinkshared service or a group of services.

The configuration of the shared feedback channel, (i.e., P-RAFCH), maybe broadcast via system information block (SIB) and may varycell-by-cell. Alternatively, the shared feedback channel configurationmay be signaled through dedicated signaling to the WTRUs that have aconnection to the radio access network (RAN), (e.g., WTRUs operating ina CELL_FACH state or active/connected states). If e.g. CDMA codes areused then the Node-B broadcasts available codes and accessslots/sub-frames and/or sub-carriers for the shared feedback channel.The access slot duration may be the same as for the conventional RACH,and may be matched, (i.e., derived), to the transmission time interval(TTI) of the downlink shared services. When a WTRU needs to providefeedback, and based on the broadcast or unicast parameters above, theWTRU randomly selects a physical resource, (e.g., a code and an accessslot), associated with a particular TTI on a particular downlink sharedservice and sends its feedback.

It should be noted that the P-RAFCH may be defined by a combination ofany physical resources including, but not limited to, code, subcarrier,time, space, etc., and the exact definition of the P-RAFCH physicalresource is not essential to the embodiments disclosed herein.

In transmission of the feedback, (i.e., the pre-defined burst), notransmit power ramp-up mechanism is used in contrast to the conventionalRACH. The WTRU may send each feedback only once and does not requireacknowledgement of its receipt from the Node-B. The transmit power forthe feedback may be determined based on the received power measured on areference channel, (e.g., common pilot channel (CPICH), HS-PDSCH, etc.),and a network-supplied offset. The offset value may be broadcast.Alternatively, the network may instruct the WTRU to use an absolutepower, and provides a rule when the WTRU is allowed to provide feedback.For example, the WTRU may be permitted to send feedback only if thereceived reference channel power is above a pre-defined value.

If the WTRU has selected a Node-B out of several synchronized Node-Bswhich transmit the same downlink transmission, the WTRU transmits a NACKonly to that selected Node-B. If the WTRU performs soft combining ofsignals from a plurality of Node-Bs in an active set, the WTRU sends aNACK to the strongest Node-B in the active set.

The WTRU may send a NACK each time the WTRU fails to decode the downlinktransmission. Alternatively, the WTRU may send a NACK after two or moresuccessive downlink transmissions have failed. For example, the WTRU maysend a NACK only if m out of n successive transmissions have failed. Thenumbers m and n may be determined by the network. For the purpose ofcounting m out of n, original transmissions, re-transmissions, both, orrelative combination of both may be counted. The ability to actuallysend the NACK may depend on some random number with probability set bythe network. The network may indicate desired transmission of the NACKon a cell or group of cells different from the one where the downlinkshared service, (e.g., MBMS), is received. The cells are indicated bythe network.

In one embodiment, the feedback may be anonymous. If the feedback goesthrough, the Node-B knows that some WTRU in the cell was not able todecode the downlink transmission in a particular instance (TTI orsub-frame). Alternatively, the WTRU ID may be signaled. In accordancewith one embodiment, the downlink shared service may be mapped to aWTRU-specific signature code that will be transmitted as the payload ofthe P-RAFCH. In accordance with another embodiment, a WTRU connection IDmay be signaled along with the feedback. In accordance with yet anotherembodiment, the access opportunities to the contention-based sharedfeedback channel may be mapped to the downlink shared service so thatthe WTRU ID may be verified based on the predefined mapping. The mappingmay be transmitted by the network.

The Node-B calibrates the transmit power and/or adjusts an MCS of thedownlink shared channel carrying the shared downlink service so that itcovers the desired coverage area, (i.e., cell or a sector of a cell),with a high likelihood. With the transmit power and/or MCS adjustment,the probability that a WTRU will not receive the downlink data in a TTIcan be set to a desired operating point, preferably near zero. Since aWTRU sending a NACK is almost certainly at the edge of the cell orsector, the downlink power computation should be done under thisassumption. Since the Node-B knows the cell or sector size, the Node-B120 may configure the downlink transmit power and/or MCS so that it doesnot significantly interfere with other signals. Consequently, only veryfew WTRUs may need to send a NACK for any single TTI. With this approachwhere feedback power is fixed, a rule may be set to prohibit WTRUs fromsending feedback.

Since a WTRU sending a NACK is almost certainly at the edge of the cellor sector, the uplink transmit power on the shared feedback channel,(e.g., P-RAFCH), may be determined under this assumption. Since theNode-B 120 knows the cell or sector size, the Node-B 120 configures theuplink transmit power such that it does not significantly interfere withother signals at the Node-B 120.

Under the above assumption, (very few NACKs expected per TTI), theNode-B 120 may allocate enough shared feedback channel resources so thatthe probability of collision for a NACK is kept low and the Node-B 120is able to receive a large number of NACKs without severely impactingthe uplink capacity. However this disclosure provides means to schedulefeedback from potentially a very large number of WTRUs.

If the Node-B 120 receives at least one NACK, the Node-B 120 may forexample schedule a retransmission for which the NACK is received and/orchange the coding and modulation characteristics of subsequenttransmissions. In this way, the HS-PDSCH operates as it conventionallydoes under normal HSDPA operation. Packet delivery is guaranteed to thesame extent as it is guaranteed under the current HARQ, (i.e., subjectto a maximum limit on re-transmissions and errors in the feedback ofNACKs).

The Node-B may maintain a threshold value and retransmit the downlinktransmission only if the number of NACKs from the WTRUs exceeds thethreshold value. While data delivery is not guaranteed, it is guaranteedthat no more than a few WTRUs are unhappy. This limits the impact on thedownlink shared service throughput of a small number of WTRUs.Alternatively, the Node-B 120 may ignore the NACKs. The Node-B 120 mayallocate no resources to the shared feedback channel to obtain the sameresult.

The Node-B 120 may pool the NACKs, (i.e., keep track of data that needsretransmission), and retransmit multiple downlink transmissions at alater time as a single packet. In this case, a sequence number andbuffering may need to be extended.

The Node-B 120 may implement the following downlink power controlmechanism for the HS-PDSCH. Let P_(n) be the HS-PDSCH power reference,(i.e., power per bit), for TTI n. If a NACK is received, the Node-B 120may set the transmit power reference for TTI (n+1) as follows:P _(n+1) =P _(n) +f(num. of NACKs)Δ_(NACK); or  Equation (1)P _(n+1) =P _(MAX).  Equation (2)If the Node-B 120 receives no NACKs, the Node-B 120 may set the transmitpower reference for TTI (n+1) as follows:P _(n+1) =P _(n)−Δ_(ACK).  Equation (3)Here, Δ_(ACK), Δ_(NACK)>0, f( ) is a positive non-decreasing (but may beconstant) function of its argument. If the Node-B 120 does not receiveany NACKs, the Node-B 120 may bring the transmit power reference down bya pre-defined decrement. As soon as a NACK is received, the transmitpower reference may be increased by a pre-defined increment. Thepre-defined increment and decrement may or may not be the same. Theincrease may depend on the number of NACKs received (but may also beconstant). The ratio of increment f(num. of NACKs)Δ_(NACK) and decrementΔ_(ACK) preferably depends on the expected probability of NACK. FIG. 4shows one possible power variation scheme of an HS-PDSCH.

The actual transmit power in TTI n depends on P_(n) and the data formatselected for the data, as it does conventionally. Additionally, amaximum and a minimum power may be set to limit the actual transmitpower.

In addition to, or as an alternative to, the transmit power control, theNode-B 120 may adjust an MCS of the downlink shared service in a similarfashion. When no NACK is received, the Node-B 120 may increase the MCSorder, and when at least one NACK is received, the Node-B 120 may lowerthe MCS order.

For both power control and MCS control, the Node-B 120 may consider theresources allocated to other services in determining the range ofpossible transmit power and MCS. For instance, if the load created byother services is low, the Node-B 120 may increase its transmissionpower and/or reduce the MCS utilized for the downlink shared services,which allows more WTRUs to decode the service.

When the Node-B 120 needs to know how many WTRUs are listening to thedownlink shared service, the Node-B 120 may poll them by temporarily,(e.g., one (1) TTI), request all WTRUs to send NACKs. For this, theNode-B 120 may send a special burst or a data sequence withintentionally erroneous CRC check. This will force all WTRUs to respondwith a NACK. The Node-B 120 counts the number of received NACKs, makingallowances for losses due to fading and collisions. Not only does thisprovide a count that should be approximately correct, but if the NACKpower is “absolute”, (as opposed to relative to a received power), adistribution of uplink channel qualities is also obtained.

FIG. 5 is a flow diagram of an example process 500 for providingfeedback for downlink shared services to WTRUs via HSDPA in accordancewith another embodiment. A WTRU receives signaling on an HS-SCCH from aNode-B while the WTRU is in a Cell_FACH state (502). The WTRU decodes adownlink transmission on an HS-PDSCH if the WTRU successfully decodes anidentity of the WTRU on the signaling on the HS-SCCH (504). The WTRUsends an acknowledgement to the Node-B based on the decoding of thedownlink transmission via a contention-based shared feedback channel(506). The transmission on the shared feedback channel and the signalingon the HS-SCCH have a fixed timing relationship. Shared downlinktransmission may also be scheduled in advance e.g. by broadcast of itsparameters without the need for specific signaling.

One shared feedback channel may comprise one scrambling code and onechannelization code, (or alternatively any combination of physicalresources), in the uplink. At least one shared feedback channel isassociated with each HS-SCCH in the downlink. The shared feedbackchannel is shared amongst all WTRUs in a CELL_FACH that are requested tomonitor the associated HS-SCCH.

Another example of a 1-bit common feedback channel is one code on OFDMAsub-carriers. Multiple codes may be defined that provide multiplefeedback channels. The codes may or may not be orthogonal.

Transmission over the shared feedback channel by different WTRUs may betime multiplexed, and follow a timing restriction with respect to thesignaling over the HS-SCCH. More specifically, a WTRU transmits an ACKor NACK message over the associated shared feedback channel at a fixedtime interval after having successfully decoded its WTRU ID, (i.e., highspeed radio network temporary identity (H-RNTI)) over the HS-SCCH. Theduration of the time interval should be set such that it is long enoughfor the WTRU to receive and decode the data on the HS-PDSCH and evaluatewhether there was an error, (i.e., cyclic redundancy check (CRC)verification), yet short enough to allow the Node-B to quicklyretransmit an erroneous transport block as part of the HARQ processing.There needs to be a one to one mapping between the downlink transmissionand the feedback.

The information and parameters related to the shared feedback channelmay be signaled to the WTRU at the same time as HS-SCCH-relatedinformation is signaled, either through an SIB over the broadcastcontrol channel (BCCH)/broadcast channel (BCH) or through dedicated RRCor other signaling, (e.g., new information element (IE) in the RRCCONNECTION SETUP message).

The transmission power at which a WTRU sends the feedback may be setbased on the received power measured on a reference channel, (e.g.,CPICH, HS-PDSCH, etc.), and a network-supplied offset value. The offsetvalue may be part of the SIB. Alternatively, the network may instructthe WTRU to use an absolute power, but provides a rule when the WTRU isallowed to provide feedback. For example, the WTRU may be allowed tosend the feedback if the received reference channel power is below apre-defined value. Alternatively, the conventional HS-SCCH may bemodified to include power control information related to thetransmission of feedback over the shared feedback channel. Power offsetor relative power command, (e.g., increase or decrease), bits may beintroduced in the HS-SCCH to adjust the transmission power of the WTRUover the shared feedback channel. Optionally, the WTRU 100 may includechannel quality information in the feedback.

An alternative scheme for sending a CQI via the P-RAFCH is disclosedhereinafter. A CQI is also transmitted via the P-RAFCH. While the CQIfeedback may be either scheduled or triggered, the Node-B must be ableto differentiate between NACK only feedback, CQI only feedback, and CQIfeedback which is triggered by a NACK, (i.e., NACK+CQI). The P-RAFCHburst includes a data type indicator for indicating NACK only, CQI onlyor NACK+CQI, a data field for carrying CQI bits if needed, and areference field for carrying a modulation phase and power reference, ifneeded.

These fields may be mapped into the burst by time division multiplexing(TDM), (i.e., each data is transmitted in its own time segment).Alternatively, the fields may be mapped into the burst by code divisionmultiplexing (CDM), (e.g., a signature based structure as in the PRACHpreamble). Alternatively, the fields may be mapped into the burst byfrequency division multiplexing (FDM). FDM is particularly appropriatefor systems, such as long term evolution (LTE), where a number ofsub-carriers may be utilized. The basic physical channel resources forcarrying these fields may be, but not necessarily, orthogonal at leastat the WTRU.

The data field, if present, may use any multi-dimensional modulationschemes with each physical channel resource (time slot, signature,carrier, etc.) providing a dimension in the modulation vector space.Some examples of possible modulation schemes are as follows:

(1) Multi-dimensional m-phase shift keying (PSK) (including binary phaseshift keying (BPSK) (m=2), quadrature phase shift keying (QPSK) (m=4)),m is an integer power of 2. The number of physical channel resourcesrequired is M/log₂ m, and additional phase and power reference isrequired.

(2) Multi-dimensional m-quadrature amplitude modulation (QAM) (includingBPSK (m=2) and QPSK (m=4)), m is an integer power of 2. The number ofphysical channel resources required is M/log₂ m, and additional phaseand power reference is required.

(3) m-ary orthogonal modulation. The number of physical channelresources required is M (i.e., m=M), and additional phase and powerreference is not needed.

(4) m-ary bi-orthogonal modulation. The number of physical channelresources required is M/2 (i.e., m=M/2), and additional phase and powerreference is required.

(5) Multi-dimensional on-off keying, (i.e., M/2 carriers are either withor without power). The number of physical channel resources required isM/2, (i.e., m=M/2), and additional phase and power reference is notrequired.

The modulation scheme to be used should be signaled to the WTRU. Certainmodulation schemes may require the use of a phase and power reference,while others do not. The reference, if required, may be sent togetherwith the data type indicator. The data type indicator and the referencefield may be sent on separate physical resources. Alternatively, onlythe data type indicator is sent and the reference field is derived fromit using decisions feedback, (i.e., the data type indicator is assumedto be demodulated correctly, which permits its re-use as a referencesignal).

Additionally, in order to avoid the explicit transmission of the datatype indicator, a CQI may always be triggered by the need to transmit aNACK, (i.e., a NACK and a CQI are always sent together). Alternatively,if a NACK is sent and a CQI does not need to be sent, the data fieldcorresponding to the highest CQI value may be used. These types oftransmissions are referred to as an implicit data type format. The useof this format should be signaled to the WTRU.

The Node-B detects the presence of power over the complete burst. Ifpower is detected in a burst space, and a data type indicator is used,the Node-B reads the data type indicator. If a CQI is present, the CQIis demodulated according to the modulation scheme used. If the implicitdata type format is used, the presence of power indicates a NACK and aCQI transmission.

Because of the multicast nature of the transmissions and the need toserve most or all WTRUs, the Node-B may collect CQIs over some timeperiod. The Node-B selects the minimum CQI over this time period andschedules data rates according to the minimum CQI. In this manner allWTRUs may be highly likely to be served.

This scheme does, however, have a disadvantage that a WTRU with a badchannel condition may significantly reduce the throughput of the wholesystem. The Node-B has no way to identify that such a WTRU exists in adirect way because all feedback from the WTRUs is anonymous. In order tosolve this problem, the Node-B may collect statistics about CQItransmissions and may ignore any CQIs that are statistically very farfrom the majority. The Node-B may then select a minimum CQI from theremaining CQIs and uses that as a baseline.

Alternatively, the Node-B may select a certain small subset, (e.g.,lower 20% or lower 10%), of CQIs after the removal of outliers. TheNode-B may then use an average of these, (e.g. the actual average, amedian, etc.). Because of the multicast nature, the highest CQIs areunlikely to have any impact on the system operation. Thus, the WTRU maynot send the highest possible CQI value.

In another scheme, CQI signaling may also be implemented with 1-bitP-FRACH in the following manner. P-FRACH channel or channels may bedefined for each allowed MCS that a WTRU may request. A WTRU may signalthe channel that corresponds to the highest MCS it can support. TheNode-B may then obtain an estimate of the distribution of desired CQIand choose the MCS of the next transmission.

Another embodiment of layer 2/3 (L2/3) based operation is disclosedhereinafter. A WTRU listens to network signaling which tells the WTRU100 when, how often, and to whom to report feedback to the downlinkshared service. The WTRU decodes signals on an allocated TTI for ashared downlink service. The WTRU then collects statistics of decodingsuccess or failure rate and compares to the decoding statistics to apre-defined threshold that is provided by the network. The WTRU sendsfeedback if the decoding statistics is worse than the pre-definedthreshold.

If the WTRU has selected a Node-B out of several synchronized Node-Bswhich transmit the same data, the WTRU transmits the feedback to thatselected Node-B only. If the WTRU performs soft combining of signalsfrom a plurality of Node-Bs in an active set, the WTRU sends thefeedback to the strongest Node-B in the active set.

The network may indicate desired transmission of the NACK on a celldifferent from the one where the downlink shared service, (e.g., MBMS),is received. The cell is indicated by the network.

The downlink shared service may be mapped to a code that will betransmitted with the NACK. Alternatively WTRU connection ID may besignaled. Alternatively, if using a PRACH for the feedback, the physicalchannel access opportunities may be mapped to the downlink sharedservice. The mapping may be indicated by the network. If needed, CQIinformation may be transmitted together with the NACK or in its place.Since the signaling is at L2/3, a larger number of bits are supported ina straightforward fashion.

Some downlink shared services, (e.g., video), may use a layered QoSmechanism where certain users get higher throughput and quality thanothers. In a wireless system, an important factor that determines theQoS of a user is the throughput achievable given the location of theuser in the system. The maximum throughput achievable at cell edge istypically less than the one achievable around the cell center. Thelayered QoS may be supported without feedback from dedicated physicalchannels.

One conventional layered QoS mechanism, (e.g., digital videobroadcasting (DVB)), is based on hierarchical modulation. Inhierarchical modulation, multiple data streams, (typically ahigh-priority and a low-priority), are modulated into a single signalthat is received by all users. Users with good signal quality may decodeboth data streams while users with low signal quality may decode onlythe high-priority stream. For instance, the streams may be encoded as a16 quadrature amplitude modulation (16QAM) signal. The quadrant wherethe signal is located represents two high priority bits whereas theposition of the signal within the quadrant represents two low prioritybits. Users with good signal quality are able to decode the signal as16QAM while users with low signal quality can only decode the signal asquadrature phase shift keying (QPSK) and extract only the high prioritybits.

In accordance with the embodiments, some new signaling is provided. Fromthe network point of view, it would be unsatisfactory that all WTRUsreport their ACK or NACK feedback based on decoding of the high prioritystream only because it would lack information about the performance offavorably located WTRUs. On the other hand, having all WTRUs providingfeedback based on decoding of all streams is also unsatisfactory becausenon-favorably located WTRUs would overload the P-RAFCH with NACK.

The network sets at least one CQI threshold to determine on which streameach WTRU should provide feedback. The CQI threshold(s) is signaled fromthe network, (e.g., on the BCCH, dedicated control channel (DCCH), orMBMS control channel (MCCH) for broadcast, multicast, or unicast).

A WTRU measures its own CQI (or average CQI). The WTRU compares themeasured CQI to the CQI threshold(s) and determines the smallest CQIthreshold higher than the measured CQI. This CQI threshold correspondsto a certain subset of stream(s) that the WTRU needs to report feedback.The WTRU reports ACK or NACK feedback on the decoding of the subset ofstream(s) determined based on the CQI comparison. It is possible tofurther restrict the subset of streams to report feedback based on WTRUsubscription to the high quality service.

A particular CQI threshold may be set below which the WTRU is notallowed to provide feedback. For example, in the case that there areonly two streams, (high priority stream and low priority stream), andtwo CQI thresholds, (high CQI threshold and low CQI threshold), are set,if the measured CQI is above the high CQI threshold, the WTRU may reportfeedback on both high priority and low priority streams. If the measuredCQI is below the high CQI threshold but above the low CQI threshold, theWTRU may report feedback on the high priority stream only. If themeasured CQI is below the low CQI threshold, the WTRU may not providefeedback at all.

The Node-B may change the CQI threshold(s) from time to time based onload conditions. For instance, in case the load of the Node-B due toother services is low, the Node-B may allocate more resources to thedownlink shared services and employ less aggressive MCS to encode thestreams, which allows more WTRUs to enjoy high QoS. In case of highcontention between the downlink shared services and other services, theNode-B may use more aggressive MCS to transmit the streams therebyreducing the amount of resources for the downlink shared services.

Alternatively, the multiple streams may be transmitted separately indifferent time or using different codes. For instance, a high prioritystream may be transmitted with a less aggressive MCS while a lowpriority stream may be transmitted with a more aggressive MCS. Thisallows more flexibility in the selection of the MCS and CQI thresholdsfor decoding the streams. The disadvantage is that it is less efficientsince the streams are not combined in the same signal.

It should be noted that although the feedback mechanism above isdescribed in terms of CDMA systems, it is generic and may be applied toany wireless communication systems, and the physical channel, P-RAFCH,may be defined by a combination of any physical resources.

A method of counting the number of WTRUs which are listening to aparticular Node-B transmission by using a contentions feedback channel,(such as P-RAFCH), will be explained hereafter. Suppose that there are anumber (M) of WTRUs satisfying a configured criterion. The number ofthese WTRUs is counted by forcing each one of these WTRUs to send asignal, (e.g., ACK, NACK, PING, or the like), on the P-RAFCH.

In accordance with one embodiment, a particular physical resource, (suchas subcarrier, code, timeslot, spatial stream, or combination of these),may be allocated for each WTRU and the number of physical resource thatare actually used may be counted. This will generate a very accurateoutcome ignoring communication error. However, it may be inefficient interms of overhead because if there are a lot of WTRUs that may bepresent, a lot of physical resources are needed.

Alternatively, N physical resources may be reserved for the P-RAFCH thatthe WTRUs may access at random. The number of physical resourcesactually used is then counted, and the number of WTRUs (M) is estimatedbased on the number of used physical resources. While this estimate maynot be precise, the error may be tolerable for many applications. Thecounting error depends on the number of available physical resources (N)and the number of WTRUs (M). The number of N physical resources that isneeded for acceptable error may for example be obtained by solvingfollowing equation (4) for N:

$\begin{matrix}{M_{\max} = {\frac{c}{p}N\mspace{11mu}{\ln(N)}}} & {{Equation}\mspace{14mu}(4)}\end{matrix}$where M_(max) is the number of WTRUs that may be present, c>1 is atolerance factor, (e.g., c=2), and p is the probability with which aWTRU transmits on the P-RAFCH if the conditions for transmission aremet, which will be described in detail below. For large M_(max), N maybe significantly lower than M_(max) resulting in substantial reductionin signaling overhead in the uplink. Any other number of physicalresources may be used depending on the acceptable error.

A P-RAFCH may be a physical channel that is defined by allocating one ormore physical resources, (e.g., sub-carriers, codes, time-slots, spatialstreams, or combination of all or some of these). One or N physicalresources are reserved for the P-RAFCH for every predefined timeinterval. This predefined time interval may be referred to as a P-RAFCHframe. The P-RAFCH frame may correspond to a frame, super-frame,sub-frame, slot, etc. in different wireless communication standards.More than one P-RAFCH may be defined in a cell.

A “transmission criterion” (TC) may be defined for each P-RAFCH. A TCfor a P-RAFCH may be at least one of the following, but not limited to:

(1) Successful reception of a data packet or a block of data on aparticular downlink physical channel;

(2) Successful reception of a block of data on a particular data service(which may be spread across multiple channels);

(3) Reception of a particular signaling command;

(4) Occurrence of a measurement event; or

(5) Failure to receive a particular transmission after a specifiednumber of times.

A TC may yield a YES/NO answer, and each WTRU may be able to determineit independently without any external coordination.

FIG. 6 is a flow diagram of an example process 600 of evaluating atransmission criterion for transmitting a P-RAFCH. In each P-RAFCH framefor each P-RAFCH, a WTRU determines whether a TC associated with theP-RAFCH is satisfied (602). The TC associated with each P-RAFCH isprovided as a part of P-RAFCH setup. If the TC has not been satisfied,the process 600 ends, (i.e., the WTRU does not transmit a P-RAFCH inthis P-RAFCH frame). If the TC has been satisfied, the WTRU mayoptionally make a decision whether to send a P-RAFCH or not based on apreconfigured probability (p) of sending a P-RAFCH (604). Theprobability (p) may be set to ‘1’ so that the WTRU may always send thesignal once the TC is satisfied. If the WTRU decides not to send aP-RAFCH (606), the process ends, (i.e., the WTRU does not transmit aP-RAFCH in this P-RAFCH frame). If the WTRU decides to send a P-RAFCH(606), the WTRU determines N physical channels to choose from based onfeedback parameters 605 (607). The WTRU may then randomly select one ofN available P-RAFCH physical resources associated with the P-RAFCH(608). The WTRU then transmits a pre-defined signal using the selectedphysical resource (610). All WTRUs may transmit the same signal and thesignal may be designed in such a way that collisions are unlikely toresult in nulling of the signal, (e.g., a constant amplitude and phase).

In each P-RAFCH frame and for each P-RAFCH the Node-B estimates whethereach physical resource was used, (e.g., using a signal detectionscheme). The Node-B counts the number of used physical resources andestimates the number of WTRUs (M) accessed the P-RAFCH based on thenumber of used physical resources.

Many services and operational improvements are possible by using thenumber of WTRUs (counted or estimated). In some applications, abroadcast service transmits certain contents to users. The broadcastermay need to know how many users are listening to the channel, forexample in order to enable the broadcaster to estimate how much tocharge advertisers whose contents are broadcast on the same channel. Inthis case, it is not important to know who those listeners are, but onlyhow many of them. To this effect the listeners are instructed to send asignal (PING).

In some applications of broadcast services, the network may wish to makesure that a service is available to at least a certain number orpercentage of WTRUs in the cell. To ensure this, it needs to estimatethe total number of WTRUs attempting to receive the service and how manyof these are receiving it successfully. To do so, any two of thefollowing three quantities are needed: the number of successfulreceptions (ACKs), the number of failures (NACKs), and the number ofWTRUs present (PINGs). This may be accomplished by defining two P-RAFCHsfor the service, (for example, one for ACKs and one for NACKs, oralternatively one for PINGs and one for ACKs or NACKs). Using a totalcount (PINGs) may be preferable as this quantity is likely to remainstable for a prolonged period of time and such a count may be requestedperiodically using a more general P-RAFCH for feedback.

In both broadcast and unicast unacknowledged services, (i.e., theservices without dedicated feedback), the Node-B may wish to utilizeseveral retransmissions to ensure proper data delivery. On the otherhand, the Node-B may want to fine-tune the number of retransmissions tominimize the number of retransmissions while delivering appropriatequality of service (QoS) to at least some minimal number of WTRUs. TheP-RAFCH may be used for this object by defining TC to be lack ofsuccessful decoding after a predetermined number of retransmissions. AWTRU attempts to decode data after every re-transmission, and if theWTRU fails after a predefined number of attempts, the WTRU sends a NACKon the P-RAFCH. By counting the NACKs and estimating the number of WTRUswhich responded, the Node-B may appropriately select the number ofretransmissions which minimizes air interface usage while meeting therequired QoS. This mechanism may be used for adjusting power control forthese types of services.

The method for estimating the number of WTRUs (M) based on the number ofobserved used physical resources out of a total of N physical resourcesin a P-RAFCH frame is explained in detail. It should be noted that thisis not the only estimator that may be used, although the estimator Mprovides fairly good performance especially when M is likely to be quitelarge.

It is assumed that p=1, (i.e., a WTRU always transmits on a P-RAFCH if aTC is satisfied). It should be noted that setting p=1 is an example andp may be set differently. When p is not equal to ‘1’, equation (8) belowneeds to be multiplied by a factor of 1/p. Because the generation ofSEND/NO SEND decision for each WTRU is independent of other events, theanalysis extends to other value of p: 0<p<1, by simply multiplying theestimator by a factor of 1/p.

Let T be the number of used physical resources in a P-RAFCH frame with atotal of N physical resources. T is a random variable, 0≦T≦N. Based onthis, the number of WTRUs that actually sent feedback is estimated,(i.e., count the WTRUs which sent an ACK).

The distribution of T given M is a distribution that when M agentspicked one out of N≧1 objects (with replacement). Only T distinctobjects are actually picked. The problem is closely related to thecoupon collector problem, which is a standard combinatorial problem. Thedistribution is given as follows:

$\begin{matrix}{{{{\Pr\left\{ {T = t} \right\}} = {\frac{N!}{\left( {N - {t!}} \right)}\frac{S\left( {M,t} \right)}{N^{M}}}},{0 \leq t \leq {\min\left( {N,M} \right)}},{{\Pr\left\{ {T = t} \right\}} = 0}}{{otherwise},}} & {{Equation}\mspace{14mu}(5)}\end{matrix}$where S(M,T) is the Stirling number of the second kind:

$\begin{matrix}{{S\left( {M,t} \right)} = {\frac{1}{t!}{\sum\limits_{j = 0}^{t}\;{\left( {- 1} \right)^{j}\begin{pmatrix}t \\j\end{pmatrix}{\left( {t - j} \right)^{\; M}.}}}}} & {{Equation}\mspace{14mu}(6)}\end{matrix}$

The distribution is quite complex. In particular, the maximum likelihood(ML) estimate is difficult to obtain as maximizing Equation (4) over Mis difficult analytically or computationally. It is well known thatasymptotically:

$\begin{matrix}{{E\lbrack T\rbrack} = {{N\left( {1 - \left( {1 - \frac{1}{N}} \right)^{M}} \right)} \approx {{N\left( {1 - {\mathbb{e}}^{{- M}/N}} \right)}.}}} & {{Equation}\mspace{14mu}(7)}\end{matrix}$While equation (7) is accurate only asymptotically, it is good enough.From equation (7), the following approximate estimator may be used:

$\begin{matrix}{{\overset{\Cap}{M}(t)} = {\frac{\ln\left( {1 - \frac{t}{N}} \right)}{\ln\left( {1 - \frac{1}{N}} \right)} \approx {{- N}\mspace{11mu}{{\ln\left( {1 - \frac{t}{N}} \right)}.}}}} & {{Equation}\mspace{14mu}(8)}\end{matrix}$The approximate estimator may be used instead of the exact one to savesome complexity, if needed. It can be shown that equation (8) is theminimum variance unbiased estimator of M based on T.

If t=N, the estimate {circumflex over (M)}(N)=∞. This makes intuitivesense in the view of an ML estimation, i.e., maximizing a posteriorilikelihood. In case that all physical resources in the P-RAFCH framehave been used, the number of WTRUs that makes it most likely that thiswould happen should be infinite, absent any upper bound. Using thisintuition, a design criterion is suggested for selecting an appropriatenumber of feedback slots, given a maximum expected number of WTRUs.Specifically,

$\begin{matrix}{{{M_{\max}(N)} = {{{- {cN}}\mspace{11mu}{\ln\left( {1 - \frac{N - 1}{N}} \right)}} = {{cN}\mspace{11mu}{\ln(N)}}}},} & {{Equation}\mspace{14mu}(9)}\end{matrix}$which can be solved for N numerically given M_(max) and c is anappropriately selected constant, which may even be set larger than 1.For example, c=2 would be a reasonable choice.

Described herein are example methods for managing group communications.The example methods disclose forming subscriber groups, signaling ofgroup assignments, grouping physical channels, assigning logical orphysical channels to subscriber groups, defining triggers for activatingfeedback channels and the like. These example methods may be used in astandalone manner or in combination with any of the methods describedherein. Although the example methods may be illustrated with respect toE-MBS, the example methods are generally applicable to any form ofmulticast services, broadcast services, multimedia services, and thelike. The example methods are also applicable to machine-to-machine(M2M) communications where confirmation of commands may be desired. Theexample methods described herein are applicable everywhere where channelinformation needs to be provided efficiently to a potentially largenumber of WTRUs.

In general, grouping of subscribers may be performed bymulticast/broadcast service or by channel usage. The size of the groupmay take any integer number. For example, a group may be defined havinga size of one (1), which may be equivalent to a dedicated channel.Alternatively, very large groups may be defined to support a very largenumber of subscribers.

In an example method, the subscribers to a multicast/broadcast servicemay be partitioned into subscriber groups. For example, the subscribergroup may be defined for any use such as for negative acknowledgements,counting, or the like or for a specific use. Alternatively differentsubscriber groups may be defined for different uses.

Other features may further define the subscriber groups and/or itsmembers. For example, the subscriber groups may have a minimum number ofsubscribers or WTRUs. Although WTRUs may be referred to herein, examplemethods and embodiments are equally applicable with respect tosubscribers. In one instance, the minimum number of WTRUs per subscribergroup may be set to one. In another example, a WTRU may belong to atleast one subscriber group, but may belong to more than one subscribergroup. Thus, for example, a WTRU may belong to subscriber groups definedfor multiple services and for multiple uses per service.

In general, subscriber group assignment(s) for a WTRU may be signaledupon establishment of service, for example multicast/broadcast service,to the WTRU. The subscriber group assignment(s) may be changed later bythe base station which transmits data of the multicast/broadcast serviceor the serving base station of the WTRU. Each WTRU may be specifically(i.e., unicast) signaled its subscriber group assignment. Alternatively,group membership may be implied by, for example, the receivedmulticast/broadcast service or M2M command. Moreover, the physicalchannels that belong to a subscriber group may simply be signaled toeach subscriber. In addition, certain cell parameters may be broadcastor unicast to the WTRU. Depending on the exact number of bits assignedto specific signaling fields, example methods may be flexible enoughsuch that the base station may establish a non one-to-one mapping ofphysical (PHY) channels to subscriber groups. The base station maydefine the mapping in such a way that the mapping is one-to-one or wherethe resulting mapping ambiguity is beneficial.

Described herein is an overview of physical channel construction. Forillustration purposes only, the description is in terms of the feedbackchannel but may be applicable to any channel. The feedback controlregion, such as the multicast/broadcast service feedback control region,is an uplink (UL) PHY control region that may consist of distinctsequences modulated on an integer number of subcarriers and integernumber of orthogonal frequency-division multiple access (OFDMA) symbolsin the UL subframe for OFDM/OFDMA technology, orthogonal sequences in acertain time slot for code divisional multiple access (CDMA) technology,or the like.

The feedback region may consist of physical feedback channels. In oneexample, the physical feedback channels may form an ordered set. Inanother example, the physical feedback channels may be grouped intological channel groups. In a third example, physical feedback channelsform an ordered set and are grouped. A group of physical feedbackchannels may be called a logical feedback channel. The logical feedbackchannel therefore, if used, is a property of the cell.

Described herein is an overview of channel assignments. In one exampleassignment method, one or more logical channels may be assigned to asubscriber group. In another example assignment method, one or moreindividual physical channels may be assigned to a subscriber group.Selection of the assignment method may depend on design parameters suchas the number of subscriber groups and how dynamic the association ofWTRU is to groups. The logical channels may be used in the case where alarge number of subscriber groups exist, for example, to cover multiplemulticast/broadcast services and usages. Both assignment methods aredescribed herein below.

In general, trigger definitions for a WTRU to activate a channel, suchas a feedback channel, may be user group specific, pre-defined orsignaled by the base station. The WTRU may activate common channeltransmission upon fulfillment of trigger conditions. The activatedchannel may be selected randomly from all physical channels assigned tothe subscriber group, regardless of the method of assignment.

Described herein is an embodiment for user groups associated withlogical multicast/broadcast channels. This embodiment may not have rigidlinks between the group and the number of physical channels assigned toit. Moreover, the physical channels may be signaled at any time using afew parameters. FIG. 7 illustrates the mapping between the subscribersand physical channels. In particular, shown are the relationshipsbetween subscriber group 700 a, logical channels 710, 720 and physicalchannels 790; subscriber group 700 b, logical channels 750 and physicalchannels 790; and subscriber group 700 c, logical channels 785 andphysical channels 790.

In this embodiment, the physical channels 790 may be an ordered set. Theorder may either be known or signaled to each WTRU using broadcast orunicast signaling. If, for example, the physical channels 790 areconstructed with codes over sub-carriers in OFDM symbols (similar to anIEEE 802.16m random access or ranging preamble), then the set may beobtained by ordering the channels code-first or resource block-first, asdesired. Other similar methods may be used to obtain the ordered set.

The logical channel to physical channel mapping may be defined using atleast two methods. In a first example method, referred to as orderedlogical channel size method, all logical channels may be arranged in anarbitrary but known order. For example, the logical channels may bearranged in a decreasing order with respect to their number ofassociated physical channels. An example of such an arrangement isdefined in Table 1, which shows the number of logical channels per eachlogical channel size. The index of the logical channel, signaled to theWTRU, uniquely specifies the number and location of physical channelsthat belong to the logical channel.

TABLE 1 Number of Number of logical physical channels channels with pereach logical defined number of channel physical channels 16 L₁₆ 8 L₈ 4L₄ 2 L₂ 1 L₁

With knowledge of the above parameters and the logical channelassignment for the group (l₁, l₂, and so on), the WTRU may determine theexact physical channels as depicted in FIG. 7.

For example we may have L₁₆=2, L₈=1, L₄=1, L₂=0 and L₁=3. Then a logicalchannel sequence may be constructed as following: {(16) (16) (8) (4) (1)(1) (1)}. The number defined between the parenthesis (i.e., (.)) is thenumber of physical feedback channels in each logical channel (i.e., (16)states that there are 16 physical feedback channels in each logicalchannel, and (8) states that there are 8 physical feedback channels ineach logical channel, etc.). Starting the index from zero, an index oftwo may, for this example, inform the WTRU to use physical channels32-39. This may be illustrated as: index 0 equals positions 0-15 (thefirst “16”); index 1 equals positions 16-31 (the second “16”); and index2 equals positions 32-39 (the “8” bits).

In a second example, referred to as the arbitrary logical channel sizemethod, the logical channel may be arranged in an arbitrary order (i.e.,not by size). Then, the mapping may be explicitly signaled, which mayrequire higher overhead but may allow more flexibility. For example, alogical channel sequence may be: {16, 8, 8, 16, 4, 1, 2, 4}. Then, alogical channel index of two may tell the WTRU to use physical channelsfrom 24 to 31. This may be illustrated as: index 0 equals positions 0-15(the “16”); index 1 equals positions 16-23 (the first “8”); and index 2equals positions 24-31 (the second “8” bits).

The base station may broadcast or signal specifically to the WTRU (i.e.,unicast) when the WTRU subscribes to a service at least the followingparameters: the broadcast or signal may include the multicast/broadcastphysical channel parameters as applicable, for example, number of codesand number of subcarriers per resource group. Alternatively, themulticast/broadcast physical channel parameters may be standardized orpredefined. The broadcast or signal may include ordered or arbitrarylogical to physical channel mapping information, as defined above. Itmay further include the index of logical channel or channels assigned toeach subscriber group (a single number per logical channel persubscriber group). Also included in the broadcast or signal may be thetriggers for activation of each subscriber group. The base station maysignal (i.e., unicast) to each WTRU its at least one subscriber groupassociations each time the WTRU subscribes to a service. Alternativelythe subscriber group association is implied from the service and themapping is broadcast.

To change the number of physical channels associated with any group, thebase station may broadcast the logical channel assignment of the groupas a logical channel index (single number) or may re-transmit Table 1for the ordered case or the physical channel mapping sequence for thearbitrary case or both.

Described herein is an embodiment for user groups associated withphysical feedback channels. In this embodiment, every user group may beassociated with a set of physical feedback channels. The mapping may bearbitrary in which case it may have to be specifically listed.Alternatively, it may be ordered. For example, assuming an ordered setof physical feedback channels, one may define the number of physicalfeedback channels for each subscriber group according to Table 2, whichdefines the physical channels to subscriber group assignments. The Table2 information may either be broadcast by the cell or signaledspecifically to the WTRU. This definition uniquely defines a mappingbetween the subscriber group and a set of physical feedback channels.

The base station broadcasts or signals specifically to the WTRU (i.e.,unicast) when the WTRU subscribes to a service. The broadcast or signalmay include the physical channel parameters as applicable, for example,the number of codes and number of subcarriers per resource group.Alternatively, it may be standardized or predefined. Moreover, theinformation shown in Table 2 or its equivalent and the triggers foractivation of each subscriber group may be broadcast or signaled to theWTRU.

TABLE 2 Number of physical Subscriber Group channels 1 N_1 2 N_2 3 N_3 .. . . . .

In this embodiment, the subscriber group may act as the index to whichnumber of physical channels may be used.

The base station unicasts to each WTRU its at least one subscriber groupassociation(s) each time the WTRU subscribes to a service. As may beseen, changing the number of physical channels available to any groupmay require signaling the other groups.

Described herein is an embodiment where channel control based ongrouping may not exist at least from the perspective of the WTRU. As inthe other embodiments, physical channels exist and their location may beknown or signaled to the WTRU.

Also as in the other embodiments, the base station may maintainsubscriber groups as a means to logically determine the informationprovided by the feedback, scope the number of physical channels, and thelike. In this embodiment, the WTRU may not be aware of such a grouping.The following information may be signaled to a WTRU during its serviceinitialization: various triggers to activate the channel, and theassignment of the physical channels for each trigger. The assignment mayeither be a range of physical channel indexes or a set of physicalchannel indexes.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit receive unit (WTRU)comprising: a processor and a transceiver configured to receive datausing a multiple input multiple output (MIMO) transmission from each ofa plurality of synchronized network nodes, wherein the data receivedfrom each of the plurality of synchronized network nodes is the samedata; and the processor and the transceiver further configured totransmit feedback information to a single one of the plurality ofsynchronized network nodes, wherein the feedback information includesnegative acknowledgments and channel quality indicators, and wherein inresponse to the transmitted channel quality indicators, the processorand the transceiver are further configured to receive the same dataagain from the plurality of synchronized network nodes.
 2. The WTRU ofclaim 1 wherein the received same data is received by a plurality ofWTRUs.
 3. The WTRU of claim 1 wherein the WTRU is in a group of aplurality of groups of WTRUs, wherein the plurality of WTRU groupsreceives data transmitted substantially simultaneously using MIMOtransmissions from the plurality of synchronized network nodes.
 4. Amethod for use in a wireless transmit receive unit (WTRU), the methodcomprising: receiving, by the wireless transmit receive unit (WTRU),data using a multiple input multiple output (MIMO) transmission fromeach of a plurality of synchronized network nodes, wherein the datareceived from each of the plurality of synchronized network nodes is thesame data; and transmitting, by the WTRU, feedback information to asingle one of the plurality of synchronized network nodes, wherein thefeedback information includes negative acknowledgments and channelquality indicators and wherein in response to the transmitted channelquality indicators, the WTRU receives the same data again from theplurality of synchronized network nodes.
 5. The method of claim 4wherein the received same data is received by a plurality of WTRUs. 6.The method of claim 4 wherein the WTRU is in a group of a plurality ofgroups of WTRUs, wherein the plurality of WTRU groups receives datatransmitted substantially simultaneously using MIMO transmissions fromthe plurality of synchronized network nodes.
 7. A wireless network nodecomprising: a processor and a transceiver configured to transmit data toa wireless transmit receive unit (WTRU) using a multiple input multipleoutput (MIMO) transmission in a synchronized manner with a plurality ofother network nodes, wherein the data transmitted by each of theplurality of synchronized network nodes is the same data and whereineach of the plurality of synchronized network nodes transmits the samedata using a MIMO transmission; and the processor and the transceiverfurther configured to receive feedback information from the wirelesstransmit receive unit, wherein the feedback information is nottransmitted to the other network nodes, wherein the feedback informationincludes negative acknowledgments and channel quality indicators andwherein in response to the transmitted channel quality indicators, theprocessor and the transceiver are further configured to transmit thesame data again using a MIMO transmission in a synchronized manner withthe plurality of other network nodes.
 8. The wireless network node ofclaim 7 wherein the transmitted same data is received by a plurality ofWTRUs.
 9. The wireless network node of claim 7 wherein the processor andthe transceiver are further configured to transmit data to a pluralityof WTRU groups substantially simultaneously using MIMO transmissions.